How many image duplications in a paper would be acceptable? If the paper has two identical photos that represent different experiments, and the authors’ reply is: ‘Oops, we uploaded the wrong photo’, that would be acceptable. Mistakes happen, and the authors can correct the error by sending in an erratum with the correct photo(s). But should editors be equally forgiving in the case of two cases of “Oops, we made a mistake”, or other, more complicated scenarios?
- Category I duplications: simple, identical duplications.
- Category II duplications: duplications involving shift, rotation, or a flip.
- Category III duplications: parts within the same panel are duplicated or parts from other panels are duplicated into another panel.
Category I is the most likely to be the result of an honest error, while Category III is really hard to explain by an honest error and the most likely to be done intentionally.
We can probably all agree that a paper with just one Category I duplication can be addressed with a simple correction or erratum. But how about papers with multiple duplications? Or, to sing along with Britney Spears, the “Oops! I did it again”, cases?
Let’s take a look at some different, real-life examples in order of increasing severity of error. Where would you draw the line as a journal editor presented with these concerns? Which paper could get away with a correction, and which paper should be retracted? There is no clear answer, so this post is meant as a discussion starter, not as a solution.
Two instances of type I duplications
Here is a figure with two duplications, marked in orange and pink. Note that the pink boxes represent different experiments but the same protein, while the orange boxes represent different experiment and different proteins. Should a paper with not just one, but two type I duplications be corrected, or retracted?
A single type II duplication
Here is a figure that has one type II duplication. The lanes marked in red appear to look very similar, suggesting that both actin panels are derived from the same blot, while the lanes represent different time points. Should a paper with this figure-of-concern be addressed with a correction or a retraction? Assume this is the only problem with this paper.Could this be an honest error or was this done with the intention-to-mislead? There is no clear answer here, so we might give the authors the benefit of the doubt and ask for a correction, if this was the only problem with a paper.
Two instances of type II duplications
Here is another set of duplications below. In this case, there are two sets of type II duplications within the same figure. Should a paper that contains this figure, with 2 pairs of shifted duplications, be corrected or retracted?
Combinations of type I and II duplications
In this example, a single figure had a type I duplication and a type II duplication within the same figure. The authors admitted they uploaded the wrong panels – twice. How would you respond to this? Would you consider both of these errors, one of which involved a 180 degrees rotation to be correctable, or do you think there might have been an intention to mislead? There is no clear answer here.
This paper has three figures that combined show two simple duplications (albeit of different exposure, marked in pink and pale purple) and multiple shifted duplications (marked in light and dark orange). If you are a journal editor, would you accept the excuse of an author that they made some mistakes while assembling or uploading the figure, or would you retract this paper?
Type III duplications
In my opinion, a type III duplication should almost always lead to a retraction. Here are some examples. It is really hard to imagine that the duplications in the images below occurred in the Western blots, flow cytometry plot, or microscopy photo by accident.
Where would you draw the line?
There are lots of examples on PubPeer where the authors replied that they made a mistake. But after saying “Oops, another mistake” too many times, the other data in a paper become unreliable as well, and it becomes more and more likely that the mistakes were not done as the result of an honest error. But where does one draw the line? How many times can one say “Oops, I did it again”? How many mistakes can be addressed with a correction? At which point should an editor make the decision to retract the paper?
Again, I do not have a clear answer, but it is good to think about some threshold or flowchart.
Here is a proposal, meant to start the discussion, not to end it (edited):
- A single category I or II duplication might be addressed with a correction
- Two cases of a category I duplication within the same paper might be addressed with a correction
- Two category II duplications within the same paper could be a correction if there are many panels, or could be retracted
- Three or more category II duplications within the same paper should be retracted (‘Three strikes: You’re out’)
- Any combination of three or more category I/II duplications should be retracted
- Any paper with a category III duplication should be retracted
- If one group of authors has multiple papers with duplications, or if an institutional investigation has reveals misconduct in that group, it might make sense to be more strict, i.e. to retract papers even for one or two category II duplications.
Let me know what you think in the comments below.